Electric heater



J. J. BURGUN ELECTRIC HEATER Oct. 31, 1950 Filed Aug. 10, 1949 FIG?! J BURGUN INVENTOR FIG-3 ATTORNEY Patented Oct. 31, 1950 ELECTRIC HEATER Jules J. Burgun, Wilkinsburg, Pa., assignor to Edwin L. Wiegand Company, Pittsburgh, Pa., a corporation of Pennsylvania Application August 10, 1949, Serial No. 109,605

10 Claims. 1

My invention relates to electric heaters, and particularly to electric heaters incorporating means for protecting the heater against overtemperature, and the principal object of my invention is to provide an improved heater of this type.

In the drawing accompanyin this specification and forming a part of this application I have shown for purposes of illustration what I now consider to be the best mode of carrying my invention into practice particularly in respect of so-called immersion heaters employed for example in electric percolators, and in this drawmg:

Figure 1 is a vertical section through a percolator including a heater according to my invention;

Figure 2 is a bottom view of the device of Figure 1; and

Figure 3 is an enlarged section through the heater, on the line 3-3 of Figure 1.

For purposes of illustration I have indicated in the drawings a percolator l comprising a base II and a container l2, both formed of sheet-metal, the base having a fiat top I3 and the container a flat bottom I4 resting on the top l3 of the base i I, the base I i being provided with electrically-insulated connection terminals I5 and I6 and with a terminal shield 11, and the container bottom l4 and base top l3 being provided with registering apertures l8 and [9 in which is mounted the illustrated electric heater 20.

As herein shown the heater 20 comprises a sheet-metal sheath 2| formed to provide a shoulder 22 beyond which projects a screw threaded cylindrical portion 23 receiving a nut 24 serving to maintain the heater in position, a gasket 25 preferably being interposed between the shoulder 22 and container bottom [4 and a washer 26 between the base top l3 and nut 24, to assist in maintaining a tight connection and avoiding any leakage through the container and base openings l8 and I9,

In the present embodiment, within the sheath 2| is a hollow cylindrical electrical-insulating and heat-conducting ceramic core 21 on which is wound a resistor 28, and embedding the core 21 and resistor 28 is a body of heat-conducting electrical-resisting material 29 serving to electrically insulate the resistor 28 and to conduct the heat from the resistor 28 to the sheath 2| and thus to the liquid within the container I2.

According to the present species of my invention, the lower end 30 of the resistor 20 is suitably caught to the core 21 and then extends through the insulating material 28 and directly to the one connection terminal 15, and the upper end 3! of the resistor 28 is similarly caught to the core 21 and then connected to the inner end of a relatively heavy rod terminal 32 composed of copper or other electrically conductive material of high heat conductivity, located in a passage 33 in the core 21, and provided at its outer end, exteriorly of the insulating material 28, with a flattened extension 34 including an aperture 35.

With the foregoing, mounted on the other connection terminal [6 is a spring conductor 36 which is provided adjacent its free end with an aperture 31 whereby it may be positioned over and in electrical contact with the extension 34 of the terminal 32, thereby completing the circuit through the resistor 28 between the connection terminals I5 and IE, but is biased to the open-circuit position indicated by dotted lines in Figure 1, and is held in circuit-closed position only by a fusible member 38 positioned in the aperture 35 of the extension 34 of the terminal 32.

By reason of the described construction, inasmuch as the terminal 32 extends substantially within the heater 2B and is of high thermal conductivity, it will be subject to the temperature within the heater and will transmit that temperature to the extension 34 and thereby to the fusible member 38, and accordingly, upon overtemperature of the heater 20, as by reason of insufficient liquid within the container [2, the fusible member 38 will be fused, the spring conductor 36 Will be released, and the circuit through the heater will be opened, and sufiiciently quickly normally to avoid any damage to the heater or other portion of the appliance.

However, when the temperature has subsided, the apparatus may readily be restored to operating condition, merely by returning the spring conductor 36 to its position on the extension 34 and inserting a new fusible member 38.

Accordingly the present embodiment fully accomplishes at least the principal object of my invention, and on the other hand, obviously various changes and modifications may be made, within the scope of my invention, and therefore it will and is to be understood that my invention is not limited to the described embodiment, and I claim as my invention:

1. An electric heater comprising a resistor, a terminal for said resistor extending within said heater at least sufliciently to be directly subject to internal temperature of said heater, havin a portion accessible for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means located exteriorly of said heater in position to be heated by said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held. by said fusible means in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from over-temperature of said heater.

2. An electric heater comprising a resistor, a terminal for said resistor extending Within said heater at least sufiiciently to be directly subject to internal temperature of said heater, including a projecting portion for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means carried by said portion and adapted to be heated from said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held :by said fusible means in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from overtemperature of said heater.

3. An electric heater comprising a resistor, a terminal for said resistor extending within said heater at least sufficiently to be directly subject to internal temperature of said heater, including a projecting portion for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, a fusible member extending through an aperture in said portion and adapted to be heated from said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held by said fusible member in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible member resulting from over-temperature of said heater.

4. An electric heater comprising a resistor, a terminal for said resistor extending within said heater at least sufficiently to be directly subject to internal temperature of said heater, having a portion accessible for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means located exteriorly of said heater in position to be heated by said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held by said fusible means in engagement with said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from over-temperature of said heater.

5. An electric heater comprising a resistor, a terminal for said resistor extending Within said heater at least sufficiently to be directly subject to internal temperature of said heater, including a projecting portion for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means carried by said portion and adapted to be heated from said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held by said fusible means in engagement With said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from overtemperature of said heater.

6. An electric heater comprising a resistor, a terminal for said resistor extending Within said heater at least sufficiently to be directly subject to internal temperature of said heater, including a projecting portion for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, a fusible member extending through an aperture in said portion and adapted to be heated from said portion according to the temperature of said portion and thus according to the internal temperature of said heater, and spring means normally held by said fusible member in engagement with said terminal and biased to move to circuit open position upon fusion of said fusible member resulting from over-temperature of said heater.

'7. An electric heater comprising a resistor, refractory electrical insulating heat conducting material embedding said resistor and serving to electrically insulate said resistor and to conduct the heat from said resistor, a terminal for said resistor extending Within said material at least sufficiently to be directly subject to internal temperature of said heater, having a portion accessible for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means located exteriorly of said heater in position to be heated by said portion according to the temperature of said portion and thus according to the internal temperature of said heater, and spring means normally held by said fusible means in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from over-temperature of said heater.

8. An electric heater comprising a helical resistor, refractor electrical-insulating heat-conducting material embedding said resistor and serving to electrically insulate said resistor and to conduct the heat from said resistor, a terminal for said resistor extending interiorly of said resistor at least sufficiently to be directly subject to internal temperature of said heater, having a portion accessible for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means located exteriorly of said heater in position to be heated by said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held by said fusible means in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from over-temperature of said heater.

9. An electric heater comprising a helical resistor, refractory electrical-insulating heat conducting material embedding said resistor and serving to electrically insulate said resistor and to conduct the heat from said resistor, a terminal for said resistor extending within said material interiorly of said resistor at least sufficiently to be directly subject to internal temperature of said heater, having a portion accessible for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, fusible means located exteriorly of said heater in position to be heated by said portion according to the temperature of said portion and thus according to internal temperature of said heater, and spring means normally held by said fusible means in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from over-temperature of said heater.

10. An electric heater comprising a resistor, a terminal for said resistor extending within said heater at least sufficiently to be directly subject to internal temperature of said heater, having a portion accessible for electrical connection, and constructed to transmit heat to said portion, so that the temperature of said portion is responsive to internal temperature of said heater, said portion being adapted to transmit heat to fusible means located exteriorly of said heater in position to be heated by said portion according to the temperature of said portion and thus according to internal temperature of said heater,

and spring means constructed to be held by said fusible means in position closing the circuit to said terminal and biased to move to circuit open position upon fusion of said fusible means resulting from over-temperature of said heater.

JULES J. BURGUN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

